Older houses will be cheaper, but the land that they sit on will be worth more so that will depend a lot on the size of the city. ie. in a big city a really old house is probably near the core on valuable land while in a smaller city the value difference between central and suburb isn't that much.
In the same community I think new houses are comparable to almost new houses except that with new you may still have to pay for landscaping, fences and blinds to name a few things. Also with a new build you will be tempted to increase the price several times when your wife decides that the expensive granite is much nicer than the standard Corian one that comes with the house.